Distributed multicast logical router

ABSTRACT

For a managed network implementing at least one logical router having centralized and distributed components, some embodiments provide a method for processing multicast data messages at a first managed forwarding element (MFE) executing on a first host machine that implements a distributed multicast logical router and multiple logical switches logically connected to the logical router in conjunction with a set of additional MFEs executing on additional host machines. The method replicates multicast data messages received from a source data compute node (DCN), operating on the first host machine, that logically connects to a first logical switch of the multiple logical switches. The method replicates the multicast data message to a set of DCNs in the multicast group in the logical network without routing through a centralized local multicast router.

BACKGROUND

In current implementations, logical routers that are designated as local multicast routers process and replicate multicast data messages at edge nodes that serve as gateways between a logical network and external networks. In such embodiments, multicast data messages originating in the logical network are sent to the edge nodes which then replicate the packets back into the logical network. This process creates unnecessary traffic load on the system. There is therefore a need for a system that can process multicast data messages that originate and terminate in a logical network to be processed in a distributed fashion.

BRIEF SUMMARY

For a managed network implementing at least one logical router having centralized and distributed components, some embodiments provide a method for configuring a set of MFEs to implement a distributed multicast logical router and multiple logical switches to process the multicast data messages. The method sends, from a managed forwarding element (MFE) implementing the distributed multicast logical router, a multicast group query (e.g., an internet group management protocol (IGMP) query) to a set of data compute nodes (DCNs) (e.g., virtual machines, containers, etc.) that are logically connected to one of several logical switches and that execute on the same host machine as the managed forwarding element. The method receives multicast group reports from a subset of the set of DCNs and at least one of the multicast group reports specifies a multicast group of interest. The method distributes, to a set of MFEs executing on other host machines, a summarized multicast group report specifying a set of multicast groups of interest to the first MFE (i.e., multicast groups that the first MFE participates in). In some embodiments, the summarized multicast group report specifies the multicast groups specified in the multicast group reports received from the subset of DCNs.

In some embodiments, the summarized multicast group report is sent to a central controller or central controller cluster (e.g., a central control plane (CCP)). The central controller receives summarized multicast group reports from multiple MFEs executing on multiple host machines and generates aggregated distributed multicast logical router configuration information based on the summarized multicast group reports. The central controller cluster generates at least one multicast group report that the MFEs can use to populate output lists for replicating multicast group data messages. The central controller cluster distributes (e.g., through a local controller) the generated multicast group report to the MFEs implementing the distributed multicast logical router and logical switches. In some embodiments, the generated summarized report is an IGMP report, or set of IGMP reports. In other embodiments, the generated summarized report is a report including information that will allow a host machine to populate an output list (e.g., an mroute list) for a multicast group with remote MFEs or tunnel endpoints executing on remote host machines, such as, for example a virtual extensible local area network (VXLAN) tunnel endpoint (VTEP) to which a multicast data message for the multicast group will be replicated.

In other embodiments, the summarized multicast group report is distributed directly to other MFEs implementing the distributed logical multicast router and to an MFE implementing a local multicast router executing as part of an edge node. In some embodiments, the summarized multicast group reports are sent over a particular logical switch (e.g., a transit logical switch) that is not logically connected to any DCNs but is logically connected to the distributed logical multicast router and the edge multicast router executing as part of an edge node and acting as the local multicast router for the logical network. A local multicast router for a logical network in some embodiments is a particular router at the logical network edge that receives and distributes multicast data messages for the logical network and communicates interest in multicast groups to external routers (e.g., using protocol independent multicast (PIM)).

The MFEs including the first MFE, in some embodiments, use the summarized reports received from other MFEs to populate a multicast routing list for replicating data messages for the multicast groups indicated in the summarized report with an identifier for the source MFE or a tunnel endpoint (e.g., a VTEP) executing on the same host machine as the source MFE. In some embodiments, the multicast routing list also includes an output list indicating the logical switches that have local DCNs that participate in the multicast group. The method receives additional summarized multicast group reports from other host machines as they are sent out and uses them to maintain a current multicast routing list for replicating multicast data messages to the appropriate host machines (or MFEs executing on the host machines).

In some embodiments, the logical switches over which multicast group reports are sent generate logical switch output lists that identify individual DCNs and the distributed router for which a multicast data message for a particular multicast group are replicated. The logical switch in some embodiments includes a snooping function that populates the logical switch output list. In some embodiments, the logical switch output list is populated based on the data received from the multicast group reports or the central controller. It is understood that these methods of populating the output list are not exclusive and that in some embodiments both snooping and the summarized report are used to populate the output list.

In some embodiments, an MFE implementing the distributed multicast logical router acts as a multicast group proxy for the compute nodes executing on the same host machine and responds to multicast group queries sent by an edge multicast router executing as part of an edge node and acting as the local multicast router for the logical network.

In some embodiments, a method is provided for processing multicast data messages at a first managed forwarding element (MFE) executing on a first host machine that implements a distributed multicast logical router and multiple logical switches logically connected to the logical router in conjunction with a set of additional MFEs executing on additional host machines. The method receives a multicast data message for a multicast group from a source data compute node (DCN), operating on the first host machine, that logically connects to a first logical switch of the multiple logical switches. The method replicates the multicast data message to a set of DCNs in the multicast group that also operate on the first host machine. In some embodiments, the set of DCNs includes at least a one DCN logically connected to the first logical switch and, in some embodiments, another DCN logically connected to a second logical switch.

In some embodiments, the method replicates to the set of DCNs operating on the first machine by first replicating to DCNs logically connected to the first logical switch and to a logical router connected to the first logical switch. The method then logically replicates, in some embodiments, the multicast data message to other logical switches that have DCNs operating on the first host machine that have reported participating in the multicast group, for the other logical switches to replicate to those DCNs.

The method also replicates the multicast data message to other MFEs in the set of MFEs that have reported participating in the multicast group. In some embodiments, the method replicates the multicast data message to the other MFEs using an identifier of the first logical switch. In some embodiments, the other MFEs replicate to local DCNs by replicating the multicast data message to a set of DCNs logically connected to the first logical switch. In some embodiments, the other MFEs also logically replicate the data message to the logical router. The logical router in some embodiments then logically replicates the multicast data message to the logical switches that are logically connected to DCNs that have reported as participating in the multicast group, for the logical switch to replicate to those DCNs.

The method also replicates the multicast data message from the first MFE to an MFE executing on a host machine that acts as an edge node of a logical network to connect the logical network to external networks. In some embodiments, a logical router component (e.g., service router) executing on the host machine acting as an edge node also acts as a multicast router and communicates with at least one external router to report participation in multicast groups (e.g., using protocol independent multicast (PIM) messages), send multicast messages sourced within the logical network to the external router(s), and receive multicast messages from the external routers. In some embodiments, a received multicast message is forwarded to MFEs that have reported interest in the multicast group of the received multicast message based on the summarized reports of the other MFEs implementing the logical network.

The preceding Summary is intended to serve as a brief introduction to some embodiments of the invention. It is not meant to be an introduction or overview of all inventive subject matter disclosed in this document. The Detailed Description that follows and the Drawings that are referred to in the Detailed Description will further describe the embodiments described in the Summary as well as other embodiments. Accordingly, to understand all the embodiments described by this document, a full review of the Summary, Detailed Description and the Drawings is needed. Moreover, the claimed subject matters are not to be limited by the illustrative details in the Summary, Detailed Description and the Drawings, but rather are to be defined by the appended claims, because the claimed subject matters can be embodied in other specific forms without departing from the spirit of the subject matters.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth in the appended claims. However, for purposes of explanation, several embodiments of the invention are set forth in the following figures.

FIG. 1 conceptually illustrates a configuration view of a logical network.

FIG. 2 conceptually illustrates a management plane view of the logical network of FIG. 1.

FIG. 3 conceptually illustrates a physical implementation of the logical network of FIG. 1.

FIG. 4 conceptually illustrates a process of some embodiments for configuring MFEs to implement a distributed multicast logical router.

FIG. 5 conceptually illustrates a process of some embodiments for configuring MFEs to implement a distributed multicast logical router.

FIG. 6 conceptually illustrates a physical system carrying out an embodiment of the processes of FIGS. 4 and 5.

FIG. 7 conceptually illustrates a physical system carrying out an embodiment of the processes of FIG. 4.

FIG. 8 conceptually illustrates a process of some embodiments for replicating multicast data messages sourced in the logical network to DCNs in the logical network.

FIG. 9 conceptually illustrates a configuration view of a logical network in which the process of FIG. 8 is carried out.

FIG. 10 conceptually illustrates a physical system carrying out an embodiment of the process of FIG. 8 in the logical network illustrated in FIG. 9.

FIG. 11 conceptually illustrates an electronic system with which some embodiments of the invention are implemented.

DETAILED DESCRIPTION

In the following description, numerous details are set forth for the purpose of explanation. However, one of ordinary skill in the art will realize that the invention may be practiced without the use of these specific details. In other instances, well-known structures and devices are shown in block diagram form in order not to obscure the description of the invention with unnecessary detail.

For a managed network implementing at least one logical router having centralized and distributed components, some embodiments provide a method for processing multicast data messages at a first managed forwarding element (MFE) executing on a first host machine. The MFE implements a distributed multicast logical router and multiple logical switches logically connected to the logical router in conjunction with a set of additional MFEs executing on additional host machines. FIGS. 1, 2, and 3 illustrate configuration, management, and physical views of an exemplary network of some embodiments.

FIGS. 1, 2, and 3 illustrate two different views of a user-defined logical network. A user-defined logical network as used in this application, refers to a particular logical abstraction of a network. In some embodiments, the logical abstraction includes logical counterparts to network elements of a physical network such as forwarding elements (e.g., switches, hubs, routers, bridges, etc.), load balancers, and firewalls. The logical forwarding elements (e.g., a logical switch or logical router) in some embodiments are implemented by a set of MFEs (e.g., physical or virtual/software switches, or routers) executing on host machines. A particular host machine may host data compute nodes connected to multiple different logical networks and the set of MFEs implements all the logical networks to which the DCNs logically connect.

Configuration view 100 represents a logical network as designed by a user. As shown, the logical router 101 is part of a logical network 100 that includes the logical router 101 and two logical switches 102A and 102B. The two logical switches 102A and 102B each have VMs that connect to logical ports. While shown as VMs in these figures, it should be understood that other types of data compute nodes (e.g., containers, etc.) may connect to logical switches in some embodiments. The logical router 101 also includes two ports that connect to the external physical network 120. While shown with only one logical router, two logical switches, and five DCNs (VMs) in the logical network, the logical network may include any number of logical routers, switches, and DCNs. In some embodiments, logical router 101 may also be configured by a user to provide network services (e.g., load balancing, network address translation, etc.).

Logical routers (LRs) can be implemented in either a distributed manner (e.g., with the logical router processing performed in first-hop MFEs that physically couple directly to the data compute nodes) or a centralized manner (with the logical router processing performed in gateways for both north-south and east-west traffic). For centralized implementations, logical routers may be scaled out by using multiple physical boxes in order to provide additional throughput (e.g., using equal-cost multi-path (ECMP) techniques) as well as for failure protection.

In some embodiments, the logical routers may only use stateful services if implemented at least partially in a centralized (e.g., clustered) manner (to avoid the need for state-sharing between the logical router implementations). In different embodiments, these gateways (that provide centralized aspects of logical routers, as well as which form the connection to the external network for distributed LRs) may be implemented as virtual machines (sometimes referred to as Edge VMs), in other types of data compute nodes (e.g., containers), or by using the Linux-based datapath development kit (DPDK) packet processing software (e.g., as a VRF in the DPDK-based datapath).

In the management plane view 210 of the logical network, the logical switches 102A and 102B are the same, but the network controller has created two service routers (SRs) 204A and 204B, a distributed router 206 and a transit logical switch 205 for the logical router 101 depicted in user logical view 100. In some embodiments, these SRs operate in active-standby mode, with one of the SRs active and the other operating as a standby (in case of the failure of the active SR). In some embodiments, the management plane generates separate routing information bases (RIBs) for each of the router constructs 204A, 204B, and 206. That is, in addition to having separate objects created in the management/control plane, each of the router constructs 204A, 204B, and 206 is treated as a separate router with separate routes. The transit logical switch 205 then has logical ports for each of these routers, and each of the router constructs has an interface to the transit logical switch.

FIG. 3 conceptually illustrates a set of physical machines implementing the logical structures depicted in FIGS. 1 and 2. FIG. 3 includes two separate gateway machines 316 and 317 that host the two service routers 204A and 204B, respectively. In some embodiments, hosts 316 and 317 also host MFEs 330 implementing the distributed logical router and the transit logical switch. In other embodiments, the service router implements the distributed logical router and the transit logical switch. FIG. 3 also illustrates a set of host machines 325 hosting a set of managed forwarding elements (MFEs) 330 that implement the logical switches 102A and 102B and the distributed logical router 206. The MFEs connect the VMs executing on the different host machines 325 to the logical network. Additional details of the structure and function of the logical router components are described in U.S. Patent Publication 2016/0226754 which is hereby incorporated by reference.

FIG. 3 illustrates the physical distributed implementation of the logical network 100. Each of the VMs that couples to one of the logical switches 102A and 102B in the logical network 100 operates on a host machine 325. The MFEs 330 perform first-hop switching and routing for the logical switches 102A and 102B and for the logical distributed router 206 (in addition to performing switching and/or routing for other logical networks). As shown in FIG. 3, the distributed router 206 is implemented across the MFEs 330 as well as gateways 316 and 317. That is, the datapaths (e.g., in the MFEs 330, in a similar MFE in the gateways 316 and 317 or in a different form factor on the gateways) all include the necessary processing pipelines for the DR 206 (and the transit logical switch 205). Each MFE is capable of performing (logical) L2 processing for each logical switch and (logical) L3 processing for distributed routers and tunneling a data message to another host machine on which a destination DCN in the logical network executes. Further details of the packet processing of some embodiments are described in United States Patent Publication 2016/0226754, which is hereby incorporated by reference.

In some embodiments, a method is provided for configuring a set of MFEs implementing the distributed multicast logical router and multiple logical switches to process the multicast data messages. FIG. 4 conceptually illustrates a process for configuring MFEs to process multicast data messages in a distributed manner.

As used in this document, the term data packet, packet, or message refers to a collection of bits in a particular format sent across a network. It should be understood that the term data packet, packet, or message may be used herein to refer to various formatted collections of bits that may be sent across a network, such as Ethernet frames, IP packets, TCP segments, UDP datagrams, etc. While the examples below refer to data packets, packets, or messages, it should be understood that the invention should not be limited to any specific format or type of data message. Also, as used in this document, references to L2, L3, L4, and L7 layers (or layer 2, layer 3, layer 4, layer 7) are references respectively to the second data link layer, the third network layer, the fourth transport layer, and the seventh application layer of the OSI (Open System Interconnection) layer model.

FIG. 4 conceptually illustrates a process 400 for generating multicast group data for an MFE to implement a distributed multicast logical router. In some embodiments, the process 400 is performed by an MFE executing on a first host machine. The process begins (at 410) by sending a multicast group query (e.g., an IGMP query) to a set of local DCNs executing on the same host machine as the MFE. A multicast group query in some embodiments is a data message that is used to determine which multicast groups are of interest to the queried DCNs (i.e., which multicast groups the DCNs participate in).

The process then receives (at 420) the multicast group reports from the queried DCNs. In some embodiments, each received report specifies at least one multicast group of interest to a DCN. In some embodiments, a DCN sends a separate multicast group report (e.g., an IGMP report) for each multicast group in which the DCN participates. In other embodiments, a multicast group report may specify multiple multicast groups in which the DCN participates, if it participates in more than one group. In some instances, the process will receive reports from only the DCNs that participate in at least one multicast group (i.e., if a DCN does not participate in any multicast groups, it will not send a report). In addition, the multicast group reports in some embodiments include leave reports that specify a multicast group in which a DCN no longer participates.

Next, the process generates (at 430) output lists for logical switches and the distributed multicast logical router based on the multicast group reports received from the local DCNs. An output list is generated for each logical switch having at least one local DCN (i.e., a DCN executing on the same host machine as the MFE implementing the logical switch) that participates (is interested) in a particular multicast group. The output list of a logical switch identifies the DCNs logically connected to the logical switch that should receive multicast data messages belonging to the particular multicast group. In some embodiments, for each logical switch logically connected to DCNs executing on a host machine on which the process is performed, an output list is generated for each multicast group with participating DCNs logically connected to the logical switch. An output list is also generated for the distributed multicast logical router (e.g., an mroute list) that identifies the logical switches that participate in the multicast group. The use of the output lists will be described in further detail in relation to FIGS. 8, 9, and 10.

The process distributes (at 440) a summarized multicast group report to other MFEs executing on other host machines implementing the distributed multicast logical router. In some embodiments, the summarized multicast group report is sent directly to the other MFEs over a logical switch that is not logically connected to DCNs (e.g., a transit logical switch). In these embodiments, the MFEs receiving the summarized report use the information to populate the output list for the distributed multicast logical router to replicate data messages specified in the summarized multicast group report to the source MFE. In other embodiments, the summarized multicast group report is distributed to the other MFEs through a set of central controller computers (e.g., a central control plane (CCP)) that aggregates summarized reports from multiple MFEs. The use of a set of central controller computers to distribute the multicast group data is described in relation to FIG. 5 below.

The process receives (at 450) data regarding the summarized reports sent from other MFEs implementing the distributed multicast logical router. In some embodiments, the summarized multicast group report is received directly from the other MFEs over a logical switch that is not associated with DCNs (e.g., a transit logical switch). In other embodiments, the data regarding the summarized multicast group reports is received from a set of central controller computers (e.g., a central control plane (CCP)) that aggregates summarized reports from multiple MFEs. The distribution using the set of central controller computers is described in relation to FIG. 5 below.

Based on the received data regarding the summarized reports from the other MFEs, the process generates (at 460) an output list of MFEs that participate in multicast groups. An output list identifies MFEs to which multicast data messages for each multicast group are replicated. The MFEs in some embodiments are identified by a media access control (MAC) address or an internet protocol (IP) address associated with the MFE or a tunnel endpoint executing on the same host machine as the MFE. In some embodiments, the distributed multicast logical router maintains a list for each multicast group in which any DCN in the logical network participates in. In other embodiments, the output list of an MFE includes only those multicast group in which a local DCN (i.e., a DCN executing on the same host machine as the MFE) participates. The process then ends.

FIG. 5 conceptually illustrates a process 500 that is used to aggregate summarized multicast group reports and provide data regarding the aggregated reports to MFEs implementing a distributed multicast logical router. In some embodiments, the process 500 is performed by a set of controller computers acting as a central control plane (CCP). The process begins by receiving (at 510) summarized multicast group reports from several MFEs implementing the distributed multicast logical router. In some embodiments, the summarized multicast group report from a source WE specifies a set of multicast groups that DCNs executing on the same host machine as the source WE participate in. In some embodiments, the MFEs send summarized reports upon a change to the multicast group participation of the WE. In other embodiments, MFEs send summarized reports based on, for example, a randomized timer, a preset schedule, or a group participation expiration timer.

The process then generates (at 520) aggregated distributed multicast logical router configuration information based on the summarized multicast group reports. The aggregated distributed multicast logical router configuration information in some embodiments includes all the multicast groups that DCNs of the logical network participate in as well as identifying interested MFEs for each multicast group. The aggregated distributed multicast logical router configuration information in some embodiments identifies one or multiple of (1) the WE, (2) the host machine on which the MFE executes, or (3) a tunnel endpoint (e.g. virtual extensible local area network (VXLAN) tunnel endpoint (VTEP)) executing on the same host machine as the MFE. The identification in some embodiments takes the form of a data link address (e.g., MAC address) or a network layer address (e.g., an internet protocol (IP) address) It is understood that these are merely examples of how an WE or host interested in a particular multicast group are identified and other methods will be apparent to one skilled in the art.

The process generates (at 530) at least one set of data to be used by the individual MFEs to implement the distributed multicast logical router. In some embodiments, an MFE-specific multicast group report is generated for each host machine or WE executing on a host machine that includes the information necessary for the WE to implement the distributed multicast logical router. For example, an WE-specific multicast group report in some embodiments only specifies other MFEs participating in multicast groups included in the summarized report from the specific WE (i.e., multicast groups that have at least one participating DCN that executes on the same host machine as the specific MFE). In other embodiments, the process does not generate MFE-specific multicast group reports, but rather generates a generic multicast group report based on the aggregated distributed multicast logical router configuration information that allows each MFE to populate its distributed multicast logical router output list for multicast groups that DCNs in the logical network participate in.

The process then distributes (at 540) the multicast group reports generated based on the aggregated distributed multicast logical router configuration information to the MFEs (e.g., through local controllers executing on the same host machines as the MFEs). As described above, the distributed information in some embodiments is MFE-specific, while in others it is the same for all MFEs. The MFEs can then use the received information to populate their output lists for each multicast group as described above in relation to FIG. 4. In some embodiments, after an initial configuration process, the process may only distribute information in the multicast group reports indicating changes to the aggregated distributed multicast logical router configuration information for the MFEs to use to update existing output lists.

FIGS. 6 and 7 conceptually illustrate the multicast group report flows in different embodiments of the process of FIG. 4. Specifically, FIG. 6 conceptually illustrates the use of a central controller cluster 650 to aggregate the summarized multicast group reports and FIG. 7 conceptually illustrates the use of a particular logical switch (e.g., transit logical switch 205) to directly distribute summarized multicast group reports between MFEs. In data messages 1, MFE 630A sends multicast group (e.g., IGMP) queries to a set of DCNs (VMs 1, 3, and 4) executing on host 625A to determine if any DCNs on the host machine are interested in, or participating in, any multicast group.

Data messages 2 represent multicast group (e.g., IGMP) reports from each DCN in response to the query from the WE. In some embodiments, reports are sent from a particular DCN (e.g., VM1, VM3, and VM4) independent of a query when the DCN joins or leaves a multicast group. Additionally, in some embodiments each arrow for data messages 2 represents a set of multicast group reports. The set of multicast group reports is empty for a DCN that is not participating in any multicast groups. If a DCN participates in multiple multicast groups, in some embodiments, data messages 2 represents multiple multicast group reports, each for a different multicast group that the DCN participates in. In other embodiments, a single multicast group report includes multiple multicast groups that a DCN participates in.

The MFE in some embodiments summarizes the reports received in data messages 2 to create a summarized multicast group report for distribution to the other MFEs implementing the distributed multicast logical router. Data message 3 represents the MFE 630A sending the summarized multicast group report to the central controller cluster 650.

Other MFEs implementing the distributed multicast logical router also send similar data messages to determine the multicast groups in which DCNs executing on the same host machine participate. For example, MFE 630B sends a multicast group query as data message 4, receives multicast group reports as data messages 5, creates a summarized multicast group report, and distributes data message 6 to other MFEs implementing the distributed multicast logical router.

Data message 7 depicts a multicast group message sent from service router 204A (the active service router in the depicted embodiment) to indicate that it is the local multicast router that connects the logical network to the external network. Data message 7 in some embodiments is included in a set of control messages identifying service router 204A as the active service router. In embodiments with multiple active service routers, data message 7 is sent from a single active service router acting as the local multicast router for the logical network. Once the local multicast router is identified, all MFEs are configured to direct all multicast data messages originating on DCNs executing on the same host machine as the MFE to the local multicast router (e.g., service router 204A). In FIG. 6, service router executes the MFE (implementing the distributed logical router and the transit logical switch) that connects to the other MFEs executing on the other hosts.

Data messages 8 are distributed by central controller cluster 650 after multiple summarized reports have been received in, for example, data messages 3 and 6. In some embodiments, central controller cluster 650 sends out, as data messages 8, the multicast group reports it generates based on data messages 3 and 6. In some embodiments, data messages 8 are sent every time a new summarized multicast group report is received from an MFE. In other embodiments, data messages 8 are sent every time a summarized multicast group report is received that changes the aggregated distributed multicast logical router configuration information in a way that requires an update to at least one MFE's output list. As discussed above, data messages 8 may represent different information for each MFE based on the multicast groups specified in the summarized multicast group report received from the MFE. In some embodiments, only a subset of MFEs receive the information as part of data messages 8.

In some embodiments, the local multicast router (e.g., service router 204A) communicates with external routers using protocol independent multicast (PIM) to direct multicast messages from sources external to the network to the local multicast router. The local multicast router uses PIM to indicate participation in at least each multicast group in which any DCN of the logical network participates.

FIG. 7 conceptually illustrates the use of a particular logical switch (e.g., transit logical switch 205) to directly distribute summarized multicast group reports between MFEs. Data messages 1 and 2 are identical to data messages 1 and 2 in FIG. 6 in which a multicast group query is sent from the MFE to the DCNs executing on the same host machine and a multicast group report(s) is sent from the DCNs back to the MFE.

Data messages 3 represents MFE 730A sending the summarized multicast group report to each of the other MFEs implementing the distributed multicast logical router and to the MFE implementing service router 204A. In some embodiments, each service router receives the summarized multicast group reports in order for it to maintain a current multicast group output list in case the active service router fails. In other embodiments, only the active service router receives the summarized multicast group reports.

Data messages 4 represents MFE 730B sending the multicast group query to DCNs executing on host 725B. data messages 5 represents the multicast group reports sent from the DCNs to the MFE 730B. As for data messages 2, in some embodiments, each of data messages 5 represents a set of multicast group reports. The set of multicast group reports is empty for a DCN that is not participating in any multicast groups. If a DCN participates in multiple multicast groups, in some embodiments, data messages 5 represent multiple multicast group reports, each for a different multicast group in which the DCN participates. In other embodiments, a single multicast group report includes multiple multicast groups in which a DCN participates.

Data messages 6 depict MFE 730B sending its summarized multicast group report to the other MFEs implementing the distributed multicast logical router and to the MFE implementing service router 204A.

Data message 7 depicts service router 204A acting as a local multicast router for the logical network and sending multicast group queries to the DCNs in the logical network. Multicast group queries are also sent to the DCNs executing on other host machines, but are not depicted for clarity. Data message 8 depicts MFE 730A acting as a multicast proxy for the DCNs and responding to the multicast group query sent from service router 204A. In some embodiments, data message 8 represents a set of multicast group reports similar to those of data messages 2 but include all the multicast group identifiers in all of the messages received from DCNs as part of data messages 2.

Some embodiments provide a method for processing multicast data messages at a first managed forwarding element (MFE) executing on a first host machine that implements a distributed multicast logical router. The method is conceptually illustrated in FIGS. 8 and 10.

FIG. 8 conceptually illustrates a process 800 for processing multicast data messages sent from a DCN in the logical network. In some embodiments, process 800 is performed by the MFE implementing the distributed multicast logical router that executes on the same host as the DCN from which the multicast data message is sent. In discussing FIG. 8, references will be made to FIGS. 9 and 10 which conceptually illustrate a configuration view 900 of a logical network and a set of data messages that are sent in exemplary physical implementation 1010 as part of performing process 800. In some embodiments, a multicast data message indicates a particular multicast group as a destination of the data message.

Process 800 begins by receiving (at 810) a multicast data message from a DCN operating on a particular host machine. This corresponds to data message 1 in FIG. 10 which shows VM1 (a virtual machine being one example of a DCN) which is logically connected to logical switch 902A sending a multicast data message to MFE 1030A executing on the same host machine as VM1 (i.e. host machine 1025A).

After receiving the multicast data message, the process replicates (at 820) the multicast data message to local DCNs logically connected to the logical switch to which the source DCN logically connects. In FIG. 10 this is indicated by data message 2 which shows MFE 1030A sending the replicated multicast data message to VM3 which is logically connected to logical switch 902A as shown in configuration view 900 of the network. While only a single local DCN (VM3) logically connected to logical switch 902A is depicted in FIG. 9 it is understood that in some embodiments, there are multiple DCNs logically connected to each logical switch and that a subset (including all or none) of those connected DCNs participate in the multicast group.

The process then replicates (at 830) the multicast data message to the distributed multicast logical router logically connected to the logical switch. In some embodiments, a single MFE module or program executes both the logical switch and distributed multicast logical router implementations and so the replication is a logical process within the MFE. In terms of configuration view 900, the process (at 830) logically replicates the multicast data message from logical switch 902A to the logical router 901 of which the distributed multicast logical router is a component.

The process then logically replicates (at 840) the multicast data message to other logical switches that are logically connected to local DCNs that participate in the multicast group of the multicast data message. In FIG. 10 this process is not shown as it is internal to MFE 1030A. In some embodiments, the logical replication is based on the output list generated from the multicast group reports received from the DCNs executing on the same host machine as the MFE performing the logical processing of the multicast data message.

After logically replicating the multicast data message to the logical switches, the logical switches replicate (at 850) the multicast data messages to the local DCNs that (1) logically connect to the logical switch and (2) participate in the multicast group. In some embodiments, the replication is based on an output list populated based on multicast group reports sent from the DCNs to the MFE implementing the distributed multicast logical router. This replication (at 850) corresponds to data message 3 in FIG. 10 in which the MFE replicates the multicast data message to VM4 after logically replicating the multicast data message to logical switch 902B to which VM4 logically connects. FIG. 10 also illustrates that VM6 which is logically connected to logical switch 902B, but not participating in the multicast group, does not receive the replicated multicast data message. It is understood that in some embodiments many DCNs operate on each host machine and are logically connected to several logical switches but do not participate in a particular multicast group and do not therefore receive multicast data messages for those multicast groups. FIG. 10 depicts only two logical switches, two host machines executing MFEs, and six VMs in order to present a more limited logical environment that makes it easier to understand the basic structure of the multicast data message processing. However, a logical network in some embodiments includes additional logical switches and DCNs, and the physical network includes additional host machines and MFEs. Additionally, a host machine may host DCNs belonging to multiple logical networks that have logical network elements implemented by the MFE executing on the host machine.

The process (at 860) replicates the multicast data message to other MFEs executing on other host machines that have reported participation in the multicast group of the multicast data message. In some embodiments, these replicated multicast data messages are sent over tunnels (indicated in FIG. 10 as solid lines connecting MFEs). The tunnels are used to implement overlay logical networks (e.g., virtual local area networks (VLANs) or virtual extensible LANs (VXLANs)). When using tunnels to implement overlay networks some embodiments requires a virtual (or logical) network identifier (VNI) that identifies the VLAN or VXLAN to which the packet belongs. In some embodiments, the replicated multicast data message is sent to the other MFEs over the logical switch on which it was received (e.g., using a logical switch identifier (e.g., VNI) associated with logical switch 902A). In some embodiments, the time to live (TTL) of the packet is not decremented as part of the process of replicating to the other MFEs executing on other host machines. The replication to other MFEs is depicted by data message 4 of FIG. 10 in which the multicast data message is sent from MFE 1030A to MFE 1030B. It is understood that replicating to other MFEs in some embodiments takes place before or at the same time as replicating to the logical switches and ultimately the local participating DCNs. It is also understood that some MFEs in the physical network do not participate in a given multicast group and multicast data messages for that multicast group are not replicated to those MFEs.

The process replicates (at 870) the multicast data message to the MFE executing on the same host machine as the local multicast router that connects to an external network. In some embodiments, the local multicast router is a logical local multicast router selected from a set of one or more active service routers executing on a set of host machines acting as gateways for the logical network. Data message 7 of FIG. 10 illustrates MFE 1030A replicating the multicast data message to MFE 1030C. MFE 1030C uses it output list to replicate the received multicast data message to the service router 1004A as data message 8. The service router 1004A then replicates, as data message 9, the multicast data message to the external router.

FIG. 10 also illustrates multicast data message processing by MFE 1030B. MFE 1030B receives the multicast data message over the source logical switch as data message 4 and replicates it to DCNs logically connected to logical switch 902A (e.g., VM2). MFE 1030B then replicates to other logical switches and ultimately to the DCNs participating in the multicast group that are logically connected to the logical switches based on the output lists of the logical switches. However, MFE 1030B does not replicate to other MFEs or to the local multicast router so as to avoid replicating data messages to MFEs that have already received the replicated data message. In some embodiments, the MFE determines whether to replicate a multicast data message to other MFEs based on the source of a multicast data message. In some embodiments, if the source is a DCN executing on the same host as the MFE, the MFE performs process 800, but if the multicast data message is received, for example, at a tunnel endpoint executing on the host machine, from a source DCN executing on another host machine, the MFE replicates the multicast data message locally as depicted for MFE 1030B but does not send data messages corresponding to data messages 4 and 7 that are depicted as being performed by MFE 1030A.

FIG. 10 also depicts MFE 1030C that executes on the same host machine acting as an edge node on which active service router 1004A executes. In some embodiments, MFE 1030C has an output list, for multicast messages received through a tunnel from another MFE implementing the logical network, that includes only service router 1004A, as no other DCNs execute on the same host machine as MFE 1030C.

FIG. 11 conceptually illustrates an electronic system 1100 with which some embodiments of the invention are implemented. The electronic system 1100 can be used to execute any of the control, virtualization, or operating system applications described above. The electronic system 1100 may be a computer (e.g., a desktop computer, personal computer, tablet computer, server computer, mainframe, a blade computer etc.), phone, PDA, or any other sort of electronic device. Such an electronic system includes various types of computer readable media and interfaces for various other types of computer readable media. Electronic system 1100 includes a bus 1105, processing unit(s) 1110, a system memory 1125, a read-only memory 1130, a permanent storage device 1135, input devices 1140, and output devices 1145.

The bus 1105 collectively represents all system, peripheral, and chipset buses that communicatively connect the numerous internal devices of the electronic system 1100. For instance, the bus 1105 communicatively connects the processing unit(s) 1110 with the read-only memory 1130, the system memory 1125, and the permanent storage device 1135.

From these various memory units, the processing unit(s) 1110 retrieve instructions to execute and data to process in order to execute the processes of the invention. The processing unit(s) may be a single processor or a multi-core processor in different embodiments.

The read-only-memory (ROM) 1130 stores static data and instructions that are needed by the processing unit(s) 1110 and other modules of the electronic system. The permanent storage device 1135, on the other hand, is a read-and-write memory device. This device is a non-volatile memory unit that stores instructions and data even when the electronic system 1100 is off. Some embodiments of the invention use a mass-storage device (such as a magnetic or optical disk and its corresponding disk drive) as the permanent storage device 1135.

Other embodiments use a removable storage device (such as a floppy disk, flash drive, etc.) as the permanent storage device. Like the permanent storage device 1135, the system memory 1125 is a read-and-write memory device. However, unlike storage device 1135, the system memory is a volatile read-and-write memory, such as random access memory. The system memory stores some of the instructions and data that the processor needs at runtime. In some embodiments, the invention's processes are stored in the system memory 1125, the permanent storage device 1135, and/or the read-only memory 1130. From these various memory units, the processing unit(s) 1110 retrieve instructions to execute and data to process in order to execute the processes of some embodiments.

The bus 1105 also connects to the input and output devices 1140 and 1145. The input devices enable the user to communicate information and select commands to the electronic system. The input devices 1140 include alphanumeric keyboards and pointing devices (also called “cursor control devices”). The output devices 1145 display images generated by the electronic system. The output devices include printers and display devices, such as cathode ray tubes (CRT) or liquid crystal displays (LCD). Some embodiments include devices such as a touchscreen that function as both input and output devices.

Finally, as shown in FIG. 11, bus 1105 also couples electronic system 1100 to a network 1165 through a network adapter (not shown). In this manner, the computer can be a part of a network of computers (such as a local area network (“LAN”), a wide area network (“WAN”), or an Intranet, or a network of networks, such as the Internet. Any or all components of electronic system 1100 may be used in conjunction with the invention.

Some embodiments include electronic components, such as microprocessors, storage and memory that store computer program instructions in a machine-readable or computer-readable medium (alternatively referred to as computer-readable storage media, machine-readable media, or machine-readable storage media). Some examples of such computer-readable media include RAM, ROM, read-only compact discs (CD-ROM), recordable compact discs (CD-R), rewritable compact discs (CD-RW), read-only digital versatile discs (e.g., DVD-ROM, dual-layer DVD-ROM), a variety of recordable/rewritable DVDs (e.g., DVD-RAM, DVD-RW, DVD+RW, etc.), flash memory (e.g., SD cards, mini-SD cards, micro-SD cards, etc.), magnetic and/or solid state hard drives, read-only and recordable Blu-Ray® discs, ultra density optical discs, any other optical or magnetic media, and floppy disks. The computer-readable media may store a computer program that is executable by at least one processing unit and includes sets of instructions for performing various operations. Examples of computer programs or computer code include machine code, such as is produced by a compiler, and files including higher-level code that are executed by a computer, an electronic component, or a microprocessor using an interpreter.

While the above discussion primarily refers to microprocessor or multi-core processors that execute software, some embodiments are performed by one or more integrated circuits, such as application specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs). In some embodiments, such integrated circuits execute instructions that are stored on the circuit itself.

As used in this specification, the terms “computer”, “server”, “processor”, and “memory” all refer to electronic or other technological devices. These terms exclude people or groups of people. For the purposes of the specification, the terms display or displaying means displaying on an electronic device. As used in this specification, the terms “computer readable medium,” “computer readable media,” and “machine readable medium” are entirely restricted to tangible, physical objects that store information in a form that is readable by a computer. These terms exclude any wireless signals, wired download signals, and any other ephemeral signals.

This specification refers throughout to computational and network environments that include virtual machines (VMs). However, virtual machines are merely one example of data compute nodes (DCNs) or data compute end nodes, also referred to as addressable nodes. DCNs may include non-virtualized physical hosts, virtual machines, containers that run on top of a host operating system without the need for a hypervisor or separate operating system, and hypervisor kernel network interface modules.

VMs, in some embodiments, operate with their own guest operating systems on a host machine using resources of the host machine virtualized by virtualization software (e.g., a hypervisor, virtual machine monitor, etc.). The tenant (i.e., the owner of the VM) can choose which applications to operate on top of the guest operating system. Some containers, on the other hand, are constructs that run on top of a host operating system without the need for a hypervisor or separate guest operating system. In some embodiments, the host operating system uses name spaces to isolate the containers from each other and therefore provides operating-system level segregation of the different groups of applications that operate within different containers. This segregation is akin to the VM segregation that is offered in hypervisor-virtualized environments that virtualize system hardware, and thus can be viewed as a form of virtualization that isolates different groups of applications that operate in different containers. Such containers are more lightweight than VMs.

Hypervisor kernel network interface modules, in some embodiments, is a non-VM DCN that includes a network stack with a hypervisor kernel network interface and receive/transmit threads. One example of a hypervisor kernel network interface module is the vmknic module that is part of the ESXi™ hypervisor of VMware, Inc.

It should be understood that while the specification refers to VMs, the examples given could be any type of DCNs, including physical hosts, VMs, non-VM containers, and hypervisor kernel network interface modules. In fact, the example networks could include combinations of different types of DCNs in some embodiments.

While the invention has been described with reference to numerous specific details, one of ordinary skill in the art will recognize that the invention can be embodied in other specific forms without departing from the spirit of the invention. In addition, a number of the figures (including FIGS. 4, 5, and 8) conceptually illustrate processes. The specific operations of these processes may not be performed in the exact order shown and described. The specific operations may not be performed in one continuous series of operations, and different specific operations may be performed in different embodiments. Furthermore, the process could be implemented using several sub-processes, or as part of a larger macro process. Thus, one of ordinary skill in the art would understand that the invention is not to be limited by the foregoing illustrative details, but rather is to be defined by the appended claims. 

We claim:
 1. A method for processing multicast data messages at a first managed forwarding element (MFE) executing on a first host computer, the first MFE, in conjunction with a set of additional MFEs executing on additional host computers, implementing a distributed multicast logical router and a plurality of logical switches that logically connect to the distributed multicast logical router, the method comprising: receiving, from a source data compute node (DCN) that operates on the first host computer and logically connects to a first logical switch in the set of logical switches, a multicast data message to be forwarded to DCNs belonging to a particular multicast group to which the source DCN also belongs; to forward the multicast data message to a first set of local DCNs that execute on the first host computer and that have reported participating in the particular multicast group to which the source DCN belongs, replicating the multicast data message to the first set of local DCNs, the first set of local DCNs comprising at least a second DCN logically connected to the first logical switch and a third DCN logically connected to a second logical switch and not to the first logical switch; and to forward the multicast data message to a second set of DCNs (i) that execute on a set of other host computers executing other MFEs in the set of additional MFEs that have reported participating in the particular multicast group and (ii) that belong to the particular multicast group to which the source DCN belongs, replicating the multicast data message to the other MFEs in the set of additional MFEs for the other MFEs to forward to the second set of DCNs.
 2. The method of claim 1, wherein replicating the multicast data message to the first set of DCNs in the particular multicast group that operate on the first host computer comprises: performing Layer 2 (L2) processing for the first logical switch to send the multicast data message to the second DCN; and performing Layer 3 (L3) processing for the distributed logical multicast router and L2 processing for the second logical switch to send the multicast data message to the third DCN.
 3. The method of claim 1, wherein replicating the multicast data message to other MFEs comprises replicating the multicast data message using an identifier of the first logical switch.
 4. The method of claim 3, wherein a second MFE to which the multicast data message is replicated executes on a second host computer and replicates the multicast data message to a third set of DCNs executing on the second host computer that have reported participating in the particular multicast group.
 5. The method of claim 4, wherein the second MFE replicates the multicast data message to the third set of DCNs in the particular multicast group, by (i) performing L2 processing for the first logical switch to send the multicast data message to DCNs in the set of DCNs that logically connect to the first logical switch and (ii) performing L3 aprocessing for the logical router and L2 processing for at least one other logical switch to send the multicast data message to the DCNs logically connected to the at least one other logical switch that have reported participating in the particular multi cast group.
 6. The method of claim 1, wherein replicating the multicast data message to the first set of DCNs in the particular multicast group that operate on the first host computer is based on an output list identifying DCNs that have reported participating in the particular multicast group to which the multicast data message is sent.
 7. The method of claim 6, wherein the output list is populated based on multicast group reports received from the first set of DCNs in the multicast group that operate on the first host computer.
 8. The method of claim 7, wherein the set of DCNs in the particular multicast group that operate on the first host computer are a set of local receiver compute nodes that have reported participating in the particular multicast group.
 9. The method of claim 1 further comprising replicating, using a third logical switch, the multicast data message to a particular MFE executing on a host computer that operates as a gateway for the distributed logical multicast router.
 10. The method of claim 9, wherein the MFE executing on the gateway replicates the multicast data message to an external multicast router.
 11. The method of claim 9, wherein the third logical switch is a logical switch that does not logically connect to DCNs that are sources and destinations of multicast data messages.
 12. A non-transitory machine readable medium storing a program for a first managed forwarding element (MFE) which when executed by a set of processing units on a first host computer, processes multicast data messages, the first MFE, in conjunction with a set of additional MFEs executing on additional host computers, implementing a distributed multicast logical router and a plurality of logical switches that logically connect to the distributed multicast logical router, the program comprising sets of instructions for: receiving, from a source data compute node (DCN) that operates on the first host computer and logically connects to a first logical switch in the set of logical switches, a multicast data message to be forwarded to DCNs belonging to a particular multicast group to which the source DCN also belongs; to forward the multicast data message to a first set of local DCNs that execute on the first host computer and that have reported participating in the particular multicast group to which the source DCN belongs, replicating the multicast data message to the first set of local DCNs, the first set of local DCNs comprising at least a second DCN logically connected to the first logical switch and a third DCN logically connected to a second logical switch and not to the first logical switch; and to forward the multicast data message to a second set of DCNs (i) that execute on a set of other host computers executing other MFEs in the set of additional MFEs that have reported participating in the particular multicast group and (ii) that belong to the particular multicast group to which the source DCN belongs, replicating the multicast data message to the other MFEs in the set of additional MFEs for the other MFEs to forward to the second set of DCNs.
 13. The non-transitory machine readable medium of claim 12, wherein the set of instructions for replicating the multicast data message to the first set of DCNs in the particular multicast group that operate on the first host computer comprises sets of instructions for: performing layer 2 (L2) processing for the first logical switch to send the multicast data message to the second DCN; and performing layer 3 (L3) processing for the distributed logical multicast router and L2 processing for the second logical switch to send the multicast data message to the third DCN.
 14. The non-transitory machine readable medium of claim 12, wherein the set of instructions for replicating the multicast data message to other MFEs comprises a set of instructions for replicating the multicast data message using an identifier of the first logical switch.
 15. The non-transitory machine readable medium of claim 14, wherein a second MFE to which the multicast data message is replicated executes on a second host computer and replicates the multicast data message to a third set of DCNs executing on the second host computer that have reported participating in the particular multicast group.
 16. The non-transitory machine readable medium of claim 15, wherein the second MFE replicates the multicast data message to the third set of DCNs in the particular multicast group, by (i) performing L2 processing for the first logical switch to send the multicast data message to DCNs in the set of DCNs that logically connect to the first logical switch and (ii) performing L3 processing for the logical router and L2 processing for at least one other logical switch to send the multicast data message to the DCNs logically connected to the at least one other logical switch that have reported participating in the particular multicast group.
 17. The non-transitory machine readable medium of claim 12, wherein replicating the multicast data message to the first set of DCNs in the particular multicast group that operate on the first host computer is based on an output list identifying DCNs that have reported participating in the particular multicast group to which the multicast data message is sent.
 18. The non-transitory machine readable medium of claim 12 further comprising a set of instructions for replicating, using a third logical switch, the multicast data message to a particular MFE executing on a host computer that operates as a gateway for the distributed logical multicast router.
 19. The non-transitory machine readable medium of claim 18, wherein the MFE executing on the gateway replicates the multicast data message to an external multicast router.
 20. The non-transitory machine readable medium of claim 18, wherein the third logical switch is a logical switch that does not logically connect to DCNs that are sources and destinations of multicast data messages. 